Treatment of gelled, swollen polyacrylonitrile type fibers with zinc sulfoxylate formaldehyde, zinc hydrosulfoxylate formaldehyde or zinc hydrosulfite



United States Patent 3,410,647 TREATMENT OF GELLED, SWOLLEN POLY-ACRYLONITRILE TYPE FIBERS WITH ZINC SULFOXYLATE FORMALDEHYDE, ZINCHYDROSULFOXYLATE FORMALDE- HYDE 0R ZINC HYDROSULFITE Julian J.Hirshfeld, Decatur, Ala., assignor to Monsanto Company, St. Louis, Mo.,a corporation of Delaware No Drawing. Continuation-impart of applicationSer. No. 134,817, Aug. 30, 1961. This application May 10, 1965, Ser. No.454,699

4 Claims. (Cl. 8-97) ABSTRACT OF THE DISCLOSURE The invention involvestreatment of freshly spun swollen and gelled polyacrylonitrile orpolyacrylonitrile fibers with any number of conventional textilereducing agents, e.g. sodium hydrosulfite, formaldehyde sulfoxylate,thiourea dioxide, sodium theosulfate and sodium bisulfite. Specificcopolymeric fibers modified by this process are ones made up of a blendof 88% of 94% acrylonitrile and 6% vinylacetate and 12% of anothercopolymer of 50% acrylonitrile and 50% methyl vinyl pyridine.

This application is a continuation-in-part of application Ser. No.134,817, filed Aug. 30, 1961, in the name of Julian J. Hirshfeld for DyeImprovement.

This invention is related to an improved process for treating acrylicfibers. More particularly this invention is related to treating acrylicfibers to increase the basic dye uptake thereof.

The problem of dyeing textile fibers composed of at least 75 percent ofacrylonitrile has long been a hinderance to the full exploitation of theuse of this fiber in the textile field. These fibers are hydrophobic andthus resist the conventional textile dyeing methods. In the past,various methods for dyeing synthetic linear acrylonitrile polymer fibershave been developed. However these methods have not been entirelysatisfactory in that there has not been full and deep penetration of thefibers by the dyestufi, leading to crocking; the dyeing is uneven, whichsometimes leaves streaks and botches on the fibers; the lightfastnessand washfastness of these prior methods are poor because the dyestuffsare located on the periphery of the fibers and thus more susceptible toany physical action which harms the surface of the fibers. Also, themethods of the prior art do not give the best results in dyeing of heavycolors such as black, brown, maroon and navy.

An object of this invention is to provide a process for treating acrylicfibers to increase the dye uptake thereof.

Another object of this invention is to provide a fiber treating processwhich prevents crocking of acrylic fibers dyed with basic dyestuffs.

Another object of this invention is to provide a process for treatingacrylic fibers so that these fibers can be easily dyed in heavy shades.

Other objects and advantagesof this invention will become apparent fromthe hereinafter detailed description.

The objects of this invention are generally accomplished by passing theacrylic fiber through a conventional finish bath having added thereto areducing agent such as sodium hydrosulfite. The fiber is in anuncollapsed state just after it has passed through the cascade of thewet spinning system. The finish bath should be acidic in nature;however, this is not a limiting factor.

More specifically, the uncollapsed fibers after leaving the cascade ofthe wet spinning system are passed through a standard or conventionalfinish bath which generally is composed of a fiber lubricant such as awax emulsion, a fiber softener such as ethylene glycol and ananti-static agent such as a quaternary ammonium compound, to whichfinish bath a reducing agent has been added. The reducing agents whichmay be used in the practice of this invention are sodium hydrosulfite,sodium sulfoxylate, formaldehyde, zinc sulfoxylate formaldehyde, zinchydroxy sulfoxylate formaldehyde, modified hydrosulfites, zinchydrosulfite, a mixture of sodium and zinc sulfoxylate formaldehyde,thiourea dioxide, sodium thiosulfate, and sodium meta bisulfite. Theamount of reducing agent, based on the volume of the finish bath, mayvary from 0.1 percent to 10 percent with the preferred being 3.0percent. However, a larger percentage may be used, but it would not beeconomical and would render the finish bath rather viscous. The pH ofthe finish bath is not of importance to the process of this invention;however, in order to avoid damage to the fibers, the bath is maintainedat a pH in the range of 2 to 7. The temperature of the finish bath mayvary from 15 C. to 50 C., however, the temperature range does not effectthe process of this invention. Generally it requires only a second ortwo for the fibers to move through the finish bath.

When the fibers have been dried after passing through the finish bath,the dye uptake of basic dyes is remarkably increased. Thus, with theprocess of this invention, crocking is reduced to acceptable commerciallimits or eliminated all together. The lightfastness and washfastness isexcellent compared to previously dyed acrylic fibers. In addition and ofextreme importance is that with the process of this invention acrylicfibers may now be successfully dyed in heavy shades which do not bleed,show crocking and maintain excellent washfastness and lightfastness.

While this application has been generally directed to acrylic fibers, itis especially useful in the basic dyeing of polymeric materials whichare polyacrylonitrile, copolymers, including binary and ternary polymerscontaining at least percent by weight of acrylonitrile in the polymermolecule, or a blend comprising polyacrylonitrile or copolymerscomprising acrylonitrile with from 2 to 50 percent of another polymericmaterial the blend having an overall polymerized acrylonitrile contentof at least 80 percent by weight. While the preferred polymers employedin the instant invention are those containing at least 80 percent ofacrylonitrile, generally recognized as the fiber-forming acrylonitrilepolymers, it will be understood that the invention is likewiseapplicable to polymers containing less than 80 percent acrylonitrile.The acrylonitrile polymers containing less than 80 percent acrylonitrileare useful in forming films, coating compositions, molding operations,lacquers, etc.

For example, the polymer may be a copolymer of from 80 to 98 percentacrylonitrile and from 2 to 20 percent of another monomer containing the(#C linkage and copolymerizable with acrylonitrile. Suitablemonoolefinic monomers include acrylic, alpha-chloroacrylic andmethacrylic acids; the acrylates, such as methylmethacrylate,ethylmethacrylate, butylmethacrylate, methoxymethyl methacrylate,beta-chloroethyl methacrylate, and the corresponding esters of acrylicand alpha-chloroacrylic acids; vinyl chloride, vinyl fluoride, vinylbromide, vinylidenc chloride, l-chloro-I-bromo-ethylene;methacrylonitrile; acrylamide and methacrylamide; alphachloroacrylamide;or monoalkyl substitution products thereof; methylvinyl ketone; vinylcarboxylates, such as vinyl acetate, vinyl chlor-oacetate, vinylpropionate, and vinyl stearate; N-vinylimides, such asN-vinylphthalimide and N-vinylsuccinimide; methylene malonic esters;itaconic acid and itaconic esters; N-vinylcarbazole; vinyl furane; alkylvinyl esters; vinyl sulfonic acid; ethylene alpha, buta-dicarboxylicacids or their anhydrides or derivatives, such as diethylcitraconatediethylmesaconate, styrene, vinyl naphthalene; vinyl-substitutedtertiary heterocyclic amines, such as the vinylpyridines andalkyl-substituted vinylpyridines, for example, 2-vinylpyridine,4-vinylpyridine, Z-methyl-5-vinylpyridine, etc.; l-vinylirnidazole andalkyl-substituted 1-vinylimidazoles, such as 2-, 4-, orS-methyl-l-vinylilidazole, and other C-"C containing polymerizablematerials.

The polymer may be a ternary or higher interpolymer, for example,products obtaind by the interpolymerization of acrylonitrile and two ormore of any of the monomers, other than acrylonitrile, enumerated above.More specifically, and preferably, the ternary polymer comprisesacrylonitrile, methacrylonitrile, and 2vinylpy1'idine. The ternarypolymers preferably contain from 80 to 98 percent of acrylonitrile, from1 to percent of a vinylpyridine or a l-vinylimidazole, and from 1 to 18percent of another substance such as methacrylonitrile or vinylchloride.

The polymer may also be a blend of a polyacrylonitrile or of a binaryinterpolymer of from 80 to 99 percent acrylonitrile and from 1 to 20percent of at least one other C:C containing substance With from 2 to 50percent of the weight of the blend of a copolymer of from 10 to 70percent of acrylonitrile and from to 90 per cent of at least one other Ccontaining polymerizable monomer. Preferably, when the polymeric mate'-rial comprises a blend, it will be a blend of a copolymer of 90 to 98percent acrylonitrile and from 2 to 10 percent of another monoolefinicmonomer, such as vinyl acetate, which is not receptive to dyestuff, witha sufficient amount of a copolymer of substituted tertiary heterocyclicamine, such as vinylpyridine or l-vinylimidazole, to give a dyeableblend having an overall vinyl-substituted tertiary heterocyclic aminecontent of from 2 to 10 percent, based EXAMPLE 1 Forty grams of fibercomposed of at least 80 percent acrylonitrile were removed from thespinning system after it had passed through a standard finish bathcomposed of a softening agent, a lubricant and an anti-static agent, andhad been collapsed and dried. This 40 grams was then introduced into dyebath, ratio of 40 to 1 dyebath to fiber, composed of 26 percent C.I.Basic Blue 22 (Colour Index, published by the Society of Dryers andColourists and the American Association of Textile Chemists andColourists, second edition, 1956 an anthraquinone dye), 5 percent ofammonium acetate and 1 percent of acetic acid. This dye bath was broughtto the boiling point and maintained at that point for 2 hours. The fibersample was then withdrawn, rinsed and dried.

Prior to the immersing of the sample into the dye bath and after the twohour boil, the concentration of the dyestutf in the dye bath wasdetermined by the use of a transmission spectrophotometer such asSpectronic 505 made by Bauch & Lomb. The concentration of the dyestufiat the beginning was 26 percent of the Weight of the fiber sample. Afterthe conclusion of the dyeing, it was determined that the concentrationof the dyestuff in the dye bath was 18.8 percent calculated on theweight of the sample, thus indicating that the dye uptake of the samplewas 7.2 percent calculated on the weight of the sample. This was acontrol sample without the reducing agent being present in the finishbath.

4 EXAMPLE 2 Forty grams of fiber composed of 92 percent acrylonitrileand 8 percent vinyl acetate were removed from the spinning system afterit has passed through a standard finish bath composed of a conventionalsoftening agent, a conventional lubricant, a conventional anti-staticagent and 2.1 percent by volume of sodium hydrosulfite and then had beencollapsed and dried. To determine the results of the treatment this 40gram sample was then introduced into a dye bath, ratio of 40 to 1 ofdyebath to fiber, composed of 16 percent of Cl. Basic Blue 22, 5 percentof ammonium acetate and 1 percent acetic acid each based on the weightof the sample. This dye bath was brought to the boiling point andmaintained at that point for 2 hours. The fiber sample was thenwithdrawn, rinsed and dried.

Prior to the immersing of the sample into the dye bath and after the twohour boil, the concentration of the dyestuff in the dye bath wasdetermined by the use of a transmission spectrophotometer such asSpectronic 505 made by Bausch & Lomb. The concentration of the dyestuffat the beginning was 16 percent calculated on the weight of the sample.After the conclusion of the dyeing, it was determined that theconcentration of the dyestutf in the dye bath was 3.8 percent calculatedon the weight of the sample, thus indicating that the basic dye uptakeof the sample was 12.2 percent, calculated on the weight of the sample.

EXAMPLE 3 Forty grams of fiber composed of a blend of 88 percent of onecopolymer composed of 94 percent acrylonitrile and 6 percent vinylacetate and 12 percent of another copolymer composed of 50 percentacrylonitrile and 50 percent methyl vinylpyridine were removed from thespinning system after it had passed through a standard finish bathcomposed of a conventional softening agent, a conventional lubricant, aconventional anti-static agent and 2.1 percent by volume of sodiumhydrosulfite and then had been collapsed and dried. To determine theresults of the treatment this 40 grams sample was then introduced into adye bath, ratio of 40 to 1 of dye bath to fiber, composed of 16 percentof C.I. Basic Blue 22, 5 percent of ammonium acetate and 1 percent ofacetic acid each calculated on the weight of the sample. This dye bathwas brought to the boiling point and maintained at that point for 2hours. The fiber sample was then withdrawn, rinsed and dried.

Prior to the immersing of the sample into the dye bath and after the twohour boil, the concentration of the dyestuff in the dye bath wasdetermined by the use of a transmission spectrophotometer such asSpectronic 505 made by Bausch & Lomb. The concentration of the dyestutfat the beginning was 16 percent calculated on the weight of the sample.After the conclusion of the dyeing, it was determined that theconcentration of the dyestutf in the dye bath was 4 percent, calculatedon the weight of the sample thus indicating that the basic dye uptake ofthe sample was 12 percent calculated on the weight of the sample.

EXAMPLE 4 The process of Example 2 was repeated except 0.2 percent byvolume of sodium hydrosulfite was used in the finish bath. Theconcentration of the dyestufi in the dye bath after the dyeingoperation, which was used for testing purposes, was completed was 5.8percent indicating basic dye uptake of 10.2 percent.

EXAMPLE 5 The process of Example 2 was repeated except 3 percent byvolume of sodium hydrosulfite was used in the finish bath and 26 percentby weight of the sample of Cl. Basic Blue 22 was used in the testing dyebath. The concentration of the dyestufi in the dye bath after the dyeingoperation was completed was 10.3 percent indicating a basic dye uptakeof 15.7 percent.

EXAMPLE 6 The process of Example 5 was repeated except 4 percent byvolume of sodium hydrosulfite was used in the finish bath. Theconcentration of the dyestuif in the testing dye bath after the dyeingoperation was completed was 11 percent indicating a basic dye uptake ofpercent.

EXAMPLE 7 The process of Example 5 was repeated except 5 percent byvolume of sodium hydrosulfite was used in the finish bath. Theconcentration of the dyestuif in the testing dye bath after the dyeingoperation was completed was 10.3 percent indicating a basic dye uptakeof 15.7 percent.

EXAMPLE 8 The process of Example 5 was repeated except 3 percent byvolume of sodium sulfoxylate formaldehyde was used in the finish bath.The concentration of the dyestuif in the dye bath after the dyeingoperation was completed was 11.4 percent indicating a basic dye uptakeof 14.6 percent.

EXAMPLE 9 The procedure of Example 8 was repeated except a 3 percent byvolume, a 4 percent by volume and a 5 percent by volume of sodium metabisulfite were added respectively to the finish bath. The concentrationof the dyestuffs respectively in the dye baths, after the dyeingoperations were completed, were 10.0 percent, 10.6 percent and 10.7percent indicating basic dye uptakes of 16.0 percent, 15.4 percent and15.3 percent respectively.

EXAMPLE 11 The process of Example 8 was repeated except a 3 percent byvolume, a 4 percent by volume and a 5 percent by volume of zinchydrosulfite were used respectively in the finish bath. Theconcentration of the dyestuffs respectively in the dye bath after thedyeing operations were completed were 14.9 percent, 15.0 percent and15.6 percent respectively indicating basic dye uptakes of 11.0 percent,11.0 percent and 10.4 percent.

When the results of the basic dye uptake of the fibers which weretreated with a reducing agent in the finish bath are compared to thecontrol example which did not have the reducing agent in the finishbath, the tremendous improvement of the uptake of the basic dye isobvious. In several instances the improvement was over percent whichgreatly aids the further use of acrylic fibers in the textile field. Theamount of reducing agent picked up by the fiber in the finish bath isless than about 5 percent by Weight of the fiber and is usually in therange of 3-5 percent when the process is carried out as in the aboveexamples.

Many modifications of the above will be obvious to those skilled in theart without a departure from the inventive concept.

What is claimed is:

1. The method of treating synthetic linear acryonitrile fibers toincrease the basic dye uptake thereof; comprising contacting the freshlyspun fibers with a wet finish bath having added thereto a reducing agentselected from the group consisting of zinc sulfoxylate formaldehyde,zinc hydrosulfoxylate formaldehyde and zinc hydrosulfite; saidcontacting taking place when the fiber is in an uncollapsed, unorientedcondition.

2. The method of claim 1 in which the reducing agent is zinc sulfoxylateformaldehyde.

3. The method of claim 1 in which the reducing agent is zinchydrosulfoxylate formaldehyde.

4. The method of claim 1 in which the reducing agent is zinchydrosulfite.

References Cited UNITED STATES PATENTS 2,899,262 8/1959 Stanton et al.26478 X 2,936,211 5/1960 Kocay.

3,089,748 5/1963 Mogenson et al.

3,091,552 5/1963 Furness et al.

3,083,111 3/1963 Bridgeford.

OTHER REFERENCES Thorne et al., Ephraims Inorganic Chemistry, 4thedition, pages 543 and 544, pub. 1943 by Oliver and Boyd Ltd.,Edinburgh, Scotland.

NORMAN G. TORCHIN, Primary Examiner.

DONALD LEVY, Assistant Examiner.

